A traditional honour that ships make to dignitaries of their own and other nations whilst passing at sea is to ‘dress’ ship and for the crew to cheer the other vessel. Today we have a photograph taken looking forward at the bow of a destroyer whilst it is saluting another ship, happily the picture is captioned on the back so we know that this is HMS Montrose, saluting the Queen of Romania: 

Flags can be seen flying from her rigging at the bow of the ship: 

HMS Montrose was a Admiralty type destroyer leader built during the Great War, but entering service too late for that conflict. In the interwar period she had an active career including spending much time with the Mediterranean fleet. The dark uniforms worn by the crew here, however, suggest that this image was taken in Home waters: 

Looking at the career of HMS Montrose, the most likely event this image was taken at was the funeral of King George V in 1936 when the ship escorted foreign dignitaries attending the ceremony. The vessel carrying the Queen of Romania can just be made out in the middle distance: 

The Queen of Romania at this time was Queen Marie of Edinburgh. Marie was born to Prince Alfred, Duke of Edinburgh and Grand Duchess Maria Alexandrovna of Russia in 1875. She married Crown Prince Ferdinand of Romania in 1892 and became queen in 1914.